Most traditional DBMS use a record-oriented (row-based) storage layout which stores all attribute columns of a single record in contiguous storage. This layout is appropriate for efficiency with respect to Online Transaction Processing (OLTP) database workloads.
Column store does not store an entire record in physically contiguous storage. It packs one (or more) attribute column(s) from many records together in contiguous storage. The attributes of a record are logically stitched together, based on their values extracted from different columns, using a common identification token or similar logical concept (such as the same offset from different column arrays). In a data warehouse environment, column store has the advantage of only accessing necessary attribute columns for query processing to reduce input/output (I/O) and memory bandwidth.